Doesn’t make much sense for Hikaru to cheat. He competes over the board where it’s much harder to cheat, and he makes most of his money through streaming, not through competition results.
The size of his streaming audience is largely predicated on his perceived skill though. So, he may hypothetically feel pressure to cheat in order to impress his audience.
I'm not sure that translates very linearly. Most of the chess YouTube "stars" are not even GMs. Most of the viewers are hardly good players, so what you can learn from an IM is astronomical. Charisma and good at teaching are much better skills than a 1000 ELO difference imo. To your point, beating Magnus might drag a lot of people to his stream.
They watch Hikaru because he is fun while he plays and wins.
Offline, he is #4 is slow chess and #1 in Blitz.
He's not facing strong challenges on Titled Tuesday, and (like all top players) he is so good that there simply aren't enough players and data to make the empirical Elo scale work for assessing his win probabilities.
